The present invention relates generally to a method of making an article of footwear and, more particularly, to a method of vacuum forming an upper for an article of footwear.
Articles of athletic footwear often include two primary elements, an upper and a sole structure. The upper provides a comfortable covering for the foot and securely positions the foot with respect to the sole structure. The sole structure is secured to a lower portion of the upper (for example, through adhesive bonding) and is generally positioned between the foot and the ground. In addition to attenuating ground reaction forces (that is, providing cushioning) during walking, running, and other ambulatory activities, the sole structure may influence foot motions (for example, by resisting pronation), impart stability, and provide traction. Accordingly, the upper and the sole structure operate cooperatively to provide a comfortable structure that is suited for a wide variety of athletic activities.
The upper is often formed from a plurality of material elements (for example, textiles, polymer sheets, foam layers, leather, and/or synthetic leather) that are stitched, adhesively bonded, and/or thermally bonded (welded) together to form a void on the interior of the footwear for receiving a foot. More particularly, the upper forms a structure that extends over instep and toe areas of the foot, along medial and lateral sides of the foot, and around a heel area of the foot.
The sole structure may include one or more components. For example, the sole structure may include a ground-contacting sole component. The ground-contacting sole component may be fashioned from a durable and wear-resistant material (such as rubber or plastic), and may include ground-engaging members, tread patterns, and/or texturing to provide traction.
In addition, in some embodiments, the sole structure may include a midsole and/or a sockliner. The midsole, if included, may be secured to a lower surface of the upper and forms a middle portion of the sole structure. Many midsole configurations are primarily formed from a resilient polymer foam material, such as polyurethane or ethylvinylacetate, that extends throughout the length and width of the footwear. The midsole may also incorporate fluid-filled chambers, plates, moderators, or other elements that further attenuate forces, influence the motions of the foot, or impart stability, for example. The sockliner is a thin, compressible member located within the upper and positioned to extend under a lower surface of the foot to enhance footwear comfort.
The footwear components discussed above may be assembled together using various methods, including, for example, stitching, adhesives, welding, and other joining techniques. Articles of footwear may be assembled, at least in part, on a structure called a “last.” A last is a form having the general shape of a human foot. During manufacturing, an article of footwear may be assembled around a last, in order to create a shoe with the desired shape. For example, upper materials/panels may be assembled, or otherwise placed, on a last. Then other components, such as midsole components and/or ground-contacting components may be attached to the upper, while fitted on the last. A last is typically not shaped like any particular type of foot, but rather is formed having a shape wherein the dimensions are averages of many different foot types, in order to produce a shoe that fits a variety of foot types.
In some cases, the upper of the shoe may be assembled from a plurality of panels of material that are joined to one another to form the shape of the upper in the shape of a foot. This type of construction may facilitate the shaping of the contoured shapes of the shoe. It is desirable to reduce the number of panels utilized to form the upper. Reducing the number of panels may reduce weight because materials used to join the panels to one another, such as stitching and adhesives, may also be reduced. In addition, a closer and/or smoother fit may be provided by reducing the number of seams between panels. Further, for sports like soccer, where the foot is used to contact a game ball, kicking accuracy and comfort may be increased by reducing the number of seams in the upper.
Material may be formed into large contoured panels for uppers of footwear. For example, in some cases, an upper may be formed in two halves, including a medial half and a lateral half, by form pressing a sheet of upper material. For example, a positive, last-shaped mold having the shape of a last may be pressed into a negative, last-shaped mold with a sheet of upper material between the positive mold and the negative mold. It is desirable to form panels of an upper to have the contours of a shoe, while substantially maintaining a consistent thickness of the panels in tightly curved areas of the contoured sheet.
The present disclosure is directed to improvements in contouring of sheet material for footwear uppers.